remove another py2 only test
remove another py2 only test

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formatters.py
947 lines | 31.0 KiB | text/x-python | PythonLexer
# -*- coding: utf-8 -*-
"""Display formatters.
Inheritance diagram:
.. inheritance-diagram:: IPython.core.formatters
:parts: 3
"""
# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.
import abc
import json
import sys
import traceback
import warnings
from decorator import decorator
from traitlets.config.configurable import Configurable
from IPython.core.getipython import get_ipython
from IPython.utils.sentinel import Sentinel
from IPython.utils.dir2 import get_real_method
from IPython.lib import pretty
from traitlets import (
Bool, Dict, Integer, Unicode, CUnicode, ObjectName, List,
ForwardDeclaredInstance,
default, observe,
)
from IPython.utils.py3compat import (
with_metaclass, string_types, unicode_type,
)
class DisplayFormatter(Configurable):
active_types = List(Unicode(),
help="""List of currently active mime-types to display.
You can use this to set a white-list for formats to display.
Most users will not need to change this value.
""").tag(config=True)
@default('active_types')
def _active_types_default(self):
return self.format_types
@observe('active_types')
def _active_types_changed(self, change):
for key, formatter in self.formatters.items():
if key in change['new']:
formatter.enabled = True
else:
formatter.enabled = False
ipython_display_formatter = ForwardDeclaredInstance('FormatterABC')
@default('ipython_display_formatter')
def _default_formatter(self):
return IPythonDisplayFormatter(parent=self)
# A dict of formatter whose keys are format types (MIME types) and whose
# values are subclasses of BaseFormatter.
formatters = Dict()
@default('formatters')
def _formatters_default(self):
"""Activate the default formatters."""
formatter_classes = [
PlainTextFormatter,
HTMLFormatter,
MarkdownFormatter,
SVGFormatter,
PNGFormatter,
PDFFormatter,
JPEGFormatter,
LatexFormatter,
JSONFormatter,
JavascriptFormatter
]
d = {}
for cls in formatter_classes:
f = cls(parent=self)
d[f.format_type] = f
return d
def format(self, obj, include=None, exclude=None):
"""Return a format data dict for an object.
By default all format types will be computed.
The following MIME types are currently implemented:
* text/plain
* text/html
* text/markdown
* text/latex
* application/json
* application/javascript
* application/pdf
* image/png
* image/jpeg
* image/svg+xml
Parameters
----------
obj : object
The Python object whose format data will be computed.
include : list or tuple, optional
A list of format type strings (MIME types) to include in the
format data dict. If this is set *only* the format types included
in this list will be computed.
exclude : list or tuple, optional
A list of format type string (MIME types) to exclude in the format
data dict. If this is set all format types will be computed,
except for those included in this argument.
Returns
-------
(format_dict, metadata_dict) : tuple of two dicts
format_dict is a dictionary of key/value pairs, one of each format that was
generated for the object. The keys are the format types, which
will usually be MIME type strings and the values and JSON'able
data structure containing the raw data for the representation in
that format.
metadata_dict is a dictionary of metadata about each mime-type output.
Its keys will be a strict subset of the keys in format_dict.
"""
format_dict = {}
md_dict = {}
if self.ipython_display_formatter(obj):
# object handled itself, don't proceed
return {}, {}
for format_type, formatter in self.formatters.items():
if include and format_type not in include:
continue
if exclude and format_type in exclude:
continue
md = None
try:
data = formatter(obj)
except:
# FIXME: log the exception
raise
# formatters can return raw data or (data, metadata)
if isinstance(data, tuple) and len(data) == 2:
data, md = data
if data is not None:
format_dict[format_type] = data
if md is not None:
md_dict[format_type] = md
return format_dict, md_dict
@property
def format_types(self):
"""Return the format types (MIME types) of the active formatters."""
return list(self.formatters.keys())
#-----------------------------------------------------------------------------
# Formatters for specific format types (text, html, svg, etc.)
#-----------------------------------------------------------------------------
def _safe_repr(obj):
"""Try to return a repr of an object
always returns a string, at least.
"""
try:
return repr(obj)
except Exception as e:
return "un-repr-able object (%r)" % e
class FormatterWarning(UserWarning):
"""Warning class for errors in formatters"""
@decorator
def catch_format_error(method, self, *args, **kwargs):
"""show traceback on failed format call"""
try:
r = method(self, *args, **kwargs)
except NotImplementedError:
# don't warn on NotImplementedErrors
return None
except Exception:
exc_info = sys.exc_info()
ip = get_ipython()
if ip is not None:
ip.showtraceback(exc_info)
else:
traceback.print_exception(*exc_info)
return None
return self._check_return(r, args[0])
class FormatterABC(with_metaclass(abc.ABCMeta, object)):
""" Abstract base class for Formatters.
A formatter is a callable class that is responsible for computing the
raw format data for a particular format type (MIME type). For example,
an HTML formatter would have a format type of `text/html` and would return
the HTML representation of the object when called.
"""
# The format type of the data returned, usually a MIME type.
format_type = 'text/plain'
# Is the formatter enabled...
enabled = True
@abc.abstractmethod
def __call__(self, obj):
"""Return a JSON'able representation of the object.
If the object cannot be formatted by this formatter,
warn and return None.
"""
return repr(obj)
def _mod_name_key(typ):
"""Return a (__module__, __name__) tuple for a type.
Used as key in Formatter.deferred_printers.
"""
module = getattr(typ, '__module__', None)
name = getattr(typ, '__name__', None)
return (module, name)
def _get_type(obj):
"""Return the type of an instance (old and new-style)"""
return getattr(obj, '__class__', None) or type(obj)
_raise_key_error = Sentinel('_raise_key_error', __name__,
"""
Special value to raise a KeyError
Raise KeyError in `BaseFormatter.pop` if passed as the default value to `pop`
""")
class BaseFormatter(Configurable):
"""A base formatter class that is configurable.
This formatter should usually be used as the base class of all formatters.
It is a traited :class:`Configurable` class and includes an extensible
API for users to determine how their objects are formatted. The following
logic is used to find a function to format an given object.
1. The object is introspected to see if it has a method with the name
:attr:`print_method`. If is does, that object is passed to that method
for formatting.
2. If no print method is found, three internal dictionaries are consulted
to find print method: :attr:`singleton_printers`, :attr:`type_printers`
and :attr:`deferred_printers`.
Users should use these dictionaries to register functions that will be
used to compute the format data for their objects (if those objects don't
have the special print methods). The easiest way of using these
dictionaries is through the :meth:`for_type` and :meth:`for_type_by_name`
methods.
If no function/callable is found to compute the format data, ``None`` is
returned and this format type is not used.
"""
format_type = Unicode('text/plain')
_return_type = string_types
enabled = Bool(True).tag(config=True)
print_method = ObjectName('__repr__')
# The singleton printers.
# Maps the IDs of the builtin singleton objects to the format functions.
singleton_printers = Dict().tag(config=True)
# The type-specific printers.
# Map type objects to the format functions.
type_printers = Dict().tag(config=True)
# The deferred-import type-specific printers.
# Map (modulename, classname) pairs to the format functions.
deferred_printers = Dict().tag(config=True)
@catch_format_error
def __call__(self, obj):
"""Compute the format for an object."""
if self.enabled:
# lookup registered printer
try:
printer = self.lookup(obj)
except KeyError:
pass
else:
return printer(obj)
# Finally look for special method names
method = get_real_method(obj, self.print_method)
if method is not None:
return method()
return None
else:
return None
def __contains__(self, typ):
"""map in to lookup_by_type"""
try:
self.lookup_by_type(typ)
except KeyError:
return False
else:
return True
def _check_return(self, r, obj):
"""Check that a return value is appropriate
Return the value if so, None otherwise, warning if invalid.
"""
if r is None or isinstance(r, self._return_type) or \
(isinstance(r, tuple) and r and isinstance(r[0], self._return_type)):
return r
else:
warnings.warn(
"%s formatter returned invalid type %s (expected %s) for object: %s" % \
(self.format_type, type(r), self._return_type, _safe_repr(obj)),
FormatterWarning
)
def lookup(self, obj):
"""Look up the formatter for a given instance.
Parameters
----------
obj : object instance
Returns
-------
f : callable
The registered formatting callable for the type.
Raises
------
KeyError if the type has not been registered.
"""
# look for singleton first
obj_id = id(obj)
if obj_id in self.singleton_printers:
return self.singleton_printers[obj_id]
# then lookup by type
return self.lookup_by_type(_get_type(obj))
def lookup_by_type(self, typ):
"""Look up the registered formatter for a type.
Parameters
----------
typ : type or '__module__.__name__' string for a type
Returns
-------
f : callable
The registered formatting callable for the type.
Raises
------
KeyError if the type has not been registered.
"""
if isinstance(typ, string_types):
typ_key = tuple(typ.rsplit('.',1))
if typ_key not in self.deferred_printers:
# We may have it cached in the type map. We will have to
# iterate over all of the types to check.
for cls in self.type_printers:
if _mod_name_key(cls) == typ_key:
return self.type_printers[cls]
else:
return self.deferred_printers[typ_key]
else:
for cls in pretty._get_mro(typ):
if cls in self.type_printers or self._in_deferred_types(cls):
return self.type_printers[cls]
# If we have reached here, the lookup failed.
raise KeyError("No registered printer for {0!r}".format(typ))
def for_type(self, typ, func=None):
"""Add a format function for a given type.
Parameters
-----------
typ : type or '__module__.__name__' string for a type
The class of the object that will be formatted using `func`.
func : callable
A callable for computing the format data.
`func` will be called with the object to be formatted,
and will return the raw data in this formatter's format.
Subclasses may use a different call signature for the
`func` argument.
If `func` is None or not specified, there will be no change,
only returning the current value.
Returns
-------
oldfunc : callable
The currently registered callable.
If you are registering a new formatter,
this will be the previous value (to enable restoring later).
"""
# if string given, interpret as 'pkg.module.class_name'
if isinstance(typ, string_types):
type_module, type_name = typ.rsplit('.', 1)
return self.for_type_by_name(type_module, type_name, func)
try:
oldfunc = self.lookup_by_type(typ)
except KeyError:
oldfunc = None
if func is not None:
self.type_printers[typ] = func
return oldfunc
def for_type_by_name(self, type_module, type_name, func=None):
"""Add a format function for a type specified by the full dotted
module and name of the type, rather than the type of the object.
Parameters
----------
type_module : str
The full dotted name of the module the type is defined in, like
``numpy``.
type_name : str
The name of the type (the class name), like ``dtype``
func : callable
A callable for computing the format data.
`func` will be called with the object to be formatted,
and will return the raw data in this formatter's format.
Subclasses may use a different call signature for the
`func` argument.
If `func` is None or unspecified, there will be no change,
only returning the current value.
Returns
-------
oldfunc : callable
The currently registered callable.
If you are registering a new formatter,
this will be the previous value (to enable restoring later).
"""
key = (type_module, type_name)
try:
oldfunc = self.lookup_by_type("%s.%s" % key)
except KeyError:
oldfunc = None
if func is not None:
self.deferred_printers[key] = func
return oldfunc
def pop(self, typ, default=_raise_key_error):
"""Pop a formatter for the given type.
Parameters
----------
typ : type or '__module__.__name__' string for a type
default : object
value to be returned if no formatter is registered for typ.
Returns
-------
obj : object
The last registered object for the type.
Raises
------
KeyError if the type is not registered and default is not specified.
"""
if isinstance(typ, string_types):
typ_key = tuple(typ.rsplit('.',1))
if typ_key not in self.deferred_printers:
# We may have it cached in the type map. We will have to
# iterate over all of the types to check.
for cls in self.type_printers:
if _mod_name_key(cls) == typ_key:
old = self.type_printers.pop(cls)
break
else:
old = default
else:
old = self.deferred_printers.pop(typ_key)
else:
if typ in self.type_printers:
old = self.type_printers.pop(typ)
else:
old = self.deferred_printers.pop(_mod_name_key(typ), default)
if old is _raise_key_error:
raise KeyError("No registered value for {0!r}".format(typ))
return old
def _in_deferred_types(self, cls):
"""
Check if the given class is specified in the deferred type registry.
Successful matches will be moved to the regular type registry for future use.
"""
mod = getattr(cls, '__module__', None)
name = getattr(cls, '__name__', None)
key = (mod, name)
if key in self.deferred_printers:
# Move the printer over to the regular registry.
printer = self.deferred_printers.pop(key)
self.type_printers[cls] = printer
return True
return False
class PlainTextFormatter(BaseFormatter):
"""The default pretty-printer.
This uses :mod:`IPython.lib.pretty` to compute the format data of
the object. If the object cannot be pretty printed, :func:`repr` is used.
See the documentation of :mod:`IPython.lib.pretty` for details on
how to write pretty printers. Here is a simple example::
def dtype_pprinter(obj, p, cycle):
if cycle:
return p.text('dtype(...)')
if hasattr(obj, 'fields'):
if obj.fields is None:
p.text(repr(obj))
else:
p.begin_group(7, 'dtype([')
for i, field in enumerate(obj.descr):
if i > 0:
p.text(',')
p.breakable()
p.pretty(field)
p.end_group(7, '])')
"""
# The format type of data returned.
format_type = Unicode('text/plain')
# This subclass ignores this attribute as it always need to return
# something.
enabled = Bool(True).tag(config=False)
max_seq_length = Integer(pretty.MAX_SEQ_LENGTH,
help="""Truncate large collections (lists, dicts, tuples, sets) to this size.
Set to 0 to disable truncation.
"""
).tag(config=True)
# Look for a _repr_pretty_ methods to use for pretty printing.
print_method = ObjectName('_repr_pretty_')
# Whether to pretty-print or not.
pprint = Bool(True).tag(config=True)
# Whether to be verbose or not.
verbose = Bool(False).tag(config=True)
# The maximum width.
max_width = Integer(79).tag(config=True)
# The newline character.
newline = Unicode('\n').tag(config=True)
# format-string for pprinting floats
float_format = Unicode('%r')
# setter for float precision, either int or direct format-string
float_precision = CUnicode('').tag(config=True)
@observe('float_precision')
def _float_precision_changed(self, change):
"""float_precision changed, set float_format accordingly.
float_precision can be set by int or str.
This will set float_format, after interpreting input.
If numpy has been imported, numpy print precision will also be set.
integer `n` sets format to '%.nf', otherwise, format set directly.
An empty string returns to defaults (repr for float, 8 for numpy).
This parameter can be set via the '%precision' magic.
"""
new = change['new']
if '%' in new:
# got explicit format string
fmt = new
try:
fmt%3.14159
except Exception:
raise ValueError("Precision must be int or format string, not %r"%new)
elif new:
# otherwise, should be an int
try:
i = int(new)
assert i >= 0
except ValueError:
raise ValueError("Precision must be int or format string, not %r"%new)
except AssertionError:
raise ValueError("int precision must be non-negative, not %r"%i)
fmt = '%%.%if'%i
if 'numpy' in sys.modules:
# set numpy precision if it has been imported
import numpy
numpy.set_printoptions(precision=i)
else:
# default back to repr
fmt = '%r'
if 'numpy' in sys.modules:
import numpy
# numpy default is 8
numpy.set_printoptions(precision=8)
self.float_format = fmt
# Use the default pretty printers from IPython.lib.pretty.
@default('singleton_printers')
def _singleton_printers_default(self):
return pretty._singleton_pprinters.copy()
@default('type_printers')
def _type_printers_default(self):
d = pretty._type_pprinters.copy()
d[float] = lambda obj,p,cycle: p.text(self.float_format%obj)
return d
@default('deferred_printers')
def _deferred_printers_default(self):
return pretty._deferred_type_pprinters.copy()
#### FormatterABC interface ####
@catch_format_error
def __call__(self, obj):
"""Compute the pretty representation of the object."""
if not self.pprint:
return repr(obj)
else:
# handle str and unicode on Python 2
# io.StringIO only accepts unicode,
# cStringIO doesn't handle unicode on py2,
# StringIO allows str, unicode but only ascii str
stream = pretty.CUnicodeIO()
printer = pretty.RepresentationPrinter(stream, self.verbose,
self.max_width, self.newline,
max_seq_length=self.max_seq_length,
singleton_pprinters=self.singleton_printers,
type_pprinters=self.type_printers,
deferred_pprinters=self.deferred_printers)
printer.pretty(obj)
printer.flush()
return stream.getvalue()
class HTMLFormatter(BaseFormatter):
"""An HTML formatter.
To define the callables that compute the HTML representation of your
objects, define a :meth:`_repr_html_` method or use the :meth:`for_type`
or :meth:`for_type_by_name` methods to register functions that handle
this.
The return value of this formatter should be a valid HTML snippet that
could be injected into an existing DOM. It should *not* include the
```<html>`` or ```<body>`` tags.
"""
format_type = Unicode('text/html')
print_method = ObjectName('_repr_html_')
class MarkdownFormatter(BaseFormatter):
"""A Markdown formatter.
To define the callables that compute the Markdown representation of your
objects, define a :meth:`_repr_markdown_` method or use the :meth:`for_type`
or :meth:`for_type_by_name` methods to register functions that handle
this.
The return value of this formatter should be a valid Markdown.
"""
format_type = Unicode('text/markdown')
print_method = ObjectName('_repr_markdown_')
class SVGFormatter(BaseFormatter):
"""An SVG formatter.
To define the callables that compute the SVG representation of your
objects, define a :meth:`_repr_svg_` method or use the :meth:`for_type`
or :meth:`for_type_by_name` methods to register functions that handle
this.
The return value of this formatter should be valid SVG enclosed in
```<svg>``` tags, that could be injected into an existing DOM. It should
*not* include the ```<html>`` or ```<body>`` tags.
"""
format_type = Unicode('image/svg+xml')
print_method = ObjectName('_repr_svg_')
class PNGFormatter(BaseFormatter):
"""A PNG formatter.
To define the callables that compute the PNG representation of your
objects, define a :meth:`_repr_png_` method or use the :meth:`for_type`
or :meth:`for_type_by_name` methods to register functions that handle
this.
The return value of this formatter should be raw PNG data, *not*
base64 encoded.
"""
format_type = Unicode('image/png')
print_method = ObjectName('_repr_png_')
_return_type = (bytes, unicode_type)
class JPEGFormatter(BaseFormatter):
"""A JPEG formatter.
To define the callables that compute the JPEG representation of your
objects, define a :meth:`_repr_jpeg_` method or use the :meth:`for_type`
or :meth:`for_type_by_name` methods to register functions that handle
this.
The return value of this formatter should be raw JPEG data, *not*
base64 encoded.
"""
format_type = Unicode('image/jpeg')
print_method = ObjectName('_repr_jpeg_')
_return_type = (bytes, unicode_type)
class LatexFormatter(BaseFormatter):
"""A LaTeX formatter.
To define the callables that compute the LaTeX representation of your
objects, define a :meth:`_repr_latex_` method or use the :meth:`for_type`
or :meth:`for_type_by_name` methods to register functions that handle
this.
The return value of this formatter should be a valid LaTeX equation,
enclosed in either ```$```, ```$$``` or another LaTeX equation
environment.
"""
format_type = Unicode('text/latex')
print_method = ObjectName('_repr_latex_')
class JSONFormatter(BaseFormatter):
"""A JSON string formatter.
To define the callables that compute the JSONable representation of
your objects, define a :meth:`_repr_json_` method or use the :meth:`for_type`
or :meth:`for_type_by_name` methods to register functions that handle
this.
The return value of this formatter should be a JSONable list or dict.
JSON scalars (None, number, string) are not allowed, only dict or list containers.
"""
format_type = Unicode('application/json')
_return_type = (list, dict)
print_method = ObjectName('_repr_json_')
def _check_return(self, r, obj):
"""Check that a return value is appropriate
Return the value if so, None otherwise, warning if invalid.
"""
if r is None:
return
md = None
if isinstance(r, tuple):
# unpack data, metadata tuple for type checking on first element
r, md = r
# handle deprecated JSON-as-string form from IPython < 3
if isinstance(r, string_types):
warnings.warn("JSON expects JSONable list/dict containers, not JSON strings",
FormatterWarning)
r = json.loads(r)
if md is not None:
# put the tuple back together
r = (r, md)
return super(JSONFormatter, self)._check_return(r, obj)
class JavascriptFormatter(BaseFormatter):
"""A Javascript formatter.
To define the callables that compute the Javascript representation of
your objects, define a :meth:`_repr_javascript_` method or use the
:meth:`for_type` or :meth:`for_type_by_name` methods to register functions
that handle this.
The return value of this formatter should be valid Javascript code and
should *not* be enclosed in ```<script>``` tags.
"""
format_type = Unicode('application/javascript')
print_method = ObjectName('_repr_javascript_')
class PDFFormatter(BaseFormatter):
"""A PDF formatter.
To define the callables that compute the PDF representation of your
objects, define a :meth:`_repr_pdf_` method or use the :meth:`for_type`
or :meth:`for_type_by_name` methods to register functions that handle
this.
The return value of this formatter should be raw PDF data, *not*
base64 encoded.
"""
format_type = Unicode('application/pdf')
print_method = ObjectName('_repr_pdf_')
_return_type = (bytes, unicode_type)
class IPythonDisplayFormatter(BaseFormatter):
"""A Formatter for objects that know how to display themselves.
To define the callables that compute the representation of your
objects, define a :meth:`_ipython_display_` method or use the :meth:`for_type`
or :meth:`for_type_by_name` methods to register functions that handle
this. Unlike mime-type displays, this method should not return anything,
instead calling any appropriate display methods itself.
This display formatter has highest priority.
If it fires, no other display formatter will be called.
"""
print_method = ObjectName('_ipython_display_')
_return_type = (type(None), bool)
@catch_format_error
def __call__(self, obj):
"""Compute the format for an object."""
if self.enabled:
# lookup registered printer
try:
printer = self.lookup(obj)
except KeyError:
pass
else:
printer(obj)
return True
# Finally look for special method names
method = get_real_method(obj, self.print_method)
if method is not None:
method()
return True
FormatterABC.register(BaseFormatter)
FormatterABC.register(PlainTextFormatter)
FormatterABC.register(HTMLFormatter)
FormatterABC.register(MarkdownFormatter)
FormatterABC.register(SVGFormatter)
FormatterABC.register(PNGFormatter)
FormatterABC.register(PDFFormatter)
FormatterABC.register(JPEGFormatter)
FormatterABC.register(LatexFormatter)
FormatterABC.register(JSONFormatter)
FormatterABC.register(JavascriptFormatter)
FormatterABC.register(IPythonDisplayFormatter)
def format_display_data(obj, include=None, exclude=None):
"""Return a format data dict for an object.
By default all format types will be computed.
The following MIME types are currently implemented:
* text/plain
* text/html
* text/markdown
* text/latex
* application/json
* application/javascript
* application/pdf
* image/png
* image/jpeg
* image/svg+xml
Parameters
----------
obj : object
The Python object whose format data will be computed.
Returns
-------
format_dict : dict
A dictionary of key/value pairs, one or each format that was
generated for the object. The keys are the format types, which
will usually be MIME type strings and the values and JSON'able
data structure containing the raw data for the representation in
that format.
include : list or tuple, optional
A list of format type strings (MIME types) to include in the
format data dict. If this is set *only* the format types included
in this list will be computed.
exclude : list or tuple, optional
A list of format type string (MIME types) to exclue in the format
data dict. If this is set all format types will be computed,
except for those included in this argument.
"""
from IPython.core.interactiveshell import InteractiveShell
return InteractiveShell.instance().display_formatter.format(
obj,
include,
exclude
)